The invention relates to a method and apparatus for measuring and controlling the application of elastomers and adhesives to a substrate.
In the manufacturing of products wherein a liquid rubber or an adhesive is applied to a substrate, such as in the tire industry, wherein an adhesive is applied to fabric reinforcement to form a reinforced component for a tire, such as a carcass ply, belt, or chafer, the liquid rubber or adhesive is often applied to the substrate in a dipping process. In the prior art, using tire manufacturing for illustrative purposes, a fabric is continuously passed through a fabric dip unit that contains one or more trays containing the liquid rubber or adhesive, such as is illustrated in U.S. Pat. No. 5,407,701, issued Apr. 18, 1995, said patent being incorporated herein by reference. The dip unit may have associated therewith, as is illustrated in FIG. 2 herein, vacuum units that are adapted to remove excess liquid rubber or adhesive from the fabric and prepare the fabric for entry into a drying oven.
Quality control of the dipping operation is provided by manual inspection supplemented by physical tests that are designed to determine the amount of adhesive or liquid rubber that has been picked up in the dipping process. One test compares the weight difference of the fabric roll before and after the fabric has undergone processing in the fabric dip unit. Another test chemically dissolves the fabric to determine the amount of adhesive. The prior art inspection methods are labor intensive, not real-time, time consuming and expensive.
For more than thirty years there have been attempts to automate the inspection of a dipped substrate. One such attempt employed a microwave sensor. Although the apparatus apparently worked for its intended purpose, a microwave sensor needs to be close to the substrate it is sensing, and the first such attempt was damaged by the first splice it encountered.
Rubel in U.S. Pat. No. 6,163,733, issued Dec. 19, 2000, describes a monitor and malfunction detector for the thread feed of a textile machine. The monitor combines electronic information and mathematical analysis of the movement of the thread, including speed, tension, and fiber consistency, thereby permitting the determination of: (1) the presence of knots and inconsistencies in the thread; (2) the operating status of the textile equipment and thread feed; (3) the prediction of problems based on the change of operating characteristics, including speed, tension, draw and duty cycle patterns; (4) the control of the textile machine being monitored; (5) the diagnosis of mechanical faults; (6) production accounting; and (7) needle burr detection.
The monitor also employs a signal comparison incorporating differential circuitry, pattern recognition, and averaging functions to achieve these goals.
Shakespeare, in U.S. Pat. No. 6,111,651, issued Aug. 29, 2000, describes an apparatus for measuring properties of a moving web. The apparatus provides a stimulus, which is directed onto the moving web by an excitation element, and the effect of the web on the stimulus is measured with a detection element. At the measuring point, the web is supported by a measurement support sheet. The measurement support sheet comprises at least two regions having different but known-responsiveness to one or more forms of stimulus, or causing different but known transformation to one or more forms of stimulus.
Stipp, in U.S. Pat. No. 6,085,437, issued Jul. 11, 2000, describes a process and apparatus for removing water from a fibrous web. In the process, the fibrous web having a moisture content of from 10% to about 90% is impinged by an oscillatory flow-reversing gas having a frequency of from 15 Hz to 1500 Hz. The apparatus includes a gas-distributing system comprising a plurality of discharge outlets designed to emit the oscillatory flow-reversing impingement gas onto the web. The impingement gas is used to remove the moisture from the web. The apparatus includes a web support designed to receive a fibrous web and to carry it in the machine direction, at least one pulse generator designed to produce oscillatory flow-reversing air or gas, and at least one gas-distributing system in fluid communication with the pulse generator.
Little, in U.S. Pat. No. 5,826,458, issued Oct. 27, 1998, describes a moisture-detection meter having a sensing head, which has a single chamber with an open top. A dielectric resonator member is provided in the chamber. The sensing head includes a field generator used to generate an oscillating electric field in the chamber. The resonator member and the field interact to produce at least one field component, which is directed out of the open top of the chamber to interact with stock passing over the sensing head. A detection device is provided to detect the frequency of resonance of the field compact after interaction with the stock, and an indicator device is provided to give an output indicative of the moisture content of the stock.
Stipp, in U.S. Pat. No. 6,134,809, issued Oct. 24, 2000, describes a process and apparatus for removing water from a fibrous web. This patent is apparently related to the earlier described Stipp patent since the description is basically the same.
Also of interest as background information for resonators used in industrial applications are xe2x80x9cDesign Aspects of Stripline Resonator Sensors for Industrial Applicationsxe2x80x9d by M. Fischer, P. Vainikainen and E. Nyfors. published as Helsinki University of Technology, Espoo (Finland), Radio Lab. Report No. S-214; xe2x80x9cMeasurement Electronics of Industrial Microwave Resonator Sensorsxe2x80x9d, (November 1991), a Ph.D. Thesis by P. V. Vainikainen; Helsinki Univ. of Technology, Espoo, Finland; xe2x80x9cPerformance Analysis of Measurement Methods of Industrial Microwave Resonator Sensorsxe2x80x9d, by P. Vainikainen, Helsinki University of Technology, Espoo, Finland, Radio Lab. 1; 1999 Institution of Electrical Engineers, all reports; xe2x80x9cProfile Inversion of Stratified Dielectric Media using the Two-Step Reconstruction, by V. A. Mikhney and P. Vainikainen, Institute of Applied Phys., Minsk, Byelorussia; Conference paper (PA) xe2x80x9cReconstruction of the Permittivity Profile using a Nonlinear Guided Wave Techniquexe2x80x9d by V. A. Mikhnev, E. Nyfors and P. Vainkainen, Helsinki Univ. of Technology, Espoo, Finland; xe2x80x9cMeasurement of Dielectrics at 100 GHz with an Open Resonator Connected in a Network Analyzerxe2x80x9d by T. M. Hirvonen, P. Vainikainen, A. Lozowski and A. V. Raisanen, Radio Lab., Helsinki Univ. of Technology, Espoo, Finland.
A method for applying a polymer to a substrate comprises the steps of (a) providing means for depositing a polymer on a substrate; (b) applying polymer to a substrate; (c) providing sensor means for detecting the amount of polymer which has been applied; (d) sensing the amount of polymer that has been applied; (e) providing vacuum means for removing excess polymer from the substrate after the polymer has been applied, and (f) removing excess polymer from said substrate.
In the illustrated embodiment, the method comprises the further steps of: (g) using a dipping operation to apply the polymer in step (b), and (h) using a resonant sensor to detect the amount of polymer applied in step (d). In the method information from the sensor in step (d) is used to control the vacuum used to remove excess polymer in step (f). Information from the sensor is combined with information from fabric specifications, line speed, adhesive formula and solids level to control polymer application and the vacuum used to remove the excess polymer.
In the illustrated embodiment, a base line resonant frequency for a specific substrate is established; a second resonant base line for the substrate coated with a desired amount of polymer is established; and the vacuum in the vacuum means is controlled using the resonant frequency data such that when the content of polymer on the substrate is too high the vacuum is increased, and when the content of the polymer is too low the vacuum is decreased.
The method may be used with tenter frames, calenders, conveyors, or any similar equipment which is used to transport a substrate.
Also provided is an apparatus for applying a polymer to a substrate comprising (a) directing and handling means for directing and handling a substrate material; (b) application means associated with the directing and handling means for applying a polymer to the substrate; (c) sensing means associated with the directing and handling means located on the directing and handling means in a location proximal to the substrate and down stream of the application means; and (d) data collection means in communication with the sensing means for accepting and collating data from the sensing means.
The apparatus may further comprise processing means associated with the data collection means and the directing and handling means for using the data from the sensing means to set operational parameters for the directing and handling means. The apparatus may comprise any conveying apparatus as described above, and sensing means comprising a resonant frequency sensor. The application means may comprise a dip through which the substrate passes. Data collection means may comprise an analyzer and the processing means may comprise a computer. The apparatus may further comprise vacuum means for removing excess dip from the substrate after application of the dip to the substrate.
When the data processing means is a computer, the computer may be programmed to control at least one of the vacuum in the vacuum means, the rate of the substrate through the equipment, the temperature of ovens associated with the equipment, and the width and other parameters of the directional handling means.
The resonant frequency sensor comprises a frequency activator and at least a pair of opposed resonator plates. A first array of resonator plates may be opposite a second array of resonator plates on each side of the substrate.
The resonator plates may be hourglass shaped. Arrays of hourglass shaped resonator plates may have a width corresponding to the width of the substrate.
It is a continuing goal in the art to reduce the expense and improve the quality of substrate processing, especially where a liquid rubber or adhesive is applied to a substrate.
Other objects of the invention will be apparent from the following description and claims.